The main factor of destruction of fuel rods in accidents with loss of coolant is associated with the vapor-zirconium reaction occurring between the fuel rod shell and the coolant (water). Improving the reliability of fuel cells can be obtained by modifying or replacing the fuel shell, materials that do not interact with the coolant during normal operation and in emergencies. The loss of coolant accident is a design-basis accident in light water reactors. The postulated accident requires an analysis of the double guillotine break in a main primary coolant pipe, which allows the coolant to freely discharge out of the primary system into the containment of the building. In the present work, the heat stored in the active zone of the reactor, the heat capacity of the fuel and the shell temperatures are determined for ATF materials U-10Mo and U3Si2. The calculated values are compared with the usually used fuel UO2. The results showed beneficial effect of using ATF materials. The above quantities are decreased dramatically for ATF, promising to replace UO2 with ATF fuels. This reduces the probabilities of accidents and oxidation in the nuclear reactors. The calculations are done for nuclear power plant, type VVER-1200.
Abstract. The paper presents numerical investigation of the thermal resistance of the contact surface of heat exchange and melt of lead. Using a geometric model of the contact area, developed on the basis of image analysis of the contact surfaces of steel and lead, the calculation of the contact resistance between molten lead and the surface of steel EP-823. The results of the calculations are compared with experimental data on thermal resistance of contact of the lead with steels EP-823 and 312 steel.
IntroductionThe future of nuclear energy is associated with the development of reactor installations on fast neutrons with sodium (BN) and lead (BREST) coolants. The use of such installations nitride nuclear fuels will improve the fuel efficiency and move to a closed fuel cycle.The fast reactors are characterized by high heat flows and temperatures in the core reactor. At temperatures above 1000 C nitride fuel begins to rapidly swell due to the increase of fission gas release. Achieving deep burnup of the fuel in such conditions is possible when you use fusible heatconducting layers between the fuel and sheath, in particular, layers of lead and its alloys. The use of thermally conductive layers reduces the temperature of the fuel, it's the swelling and gas release increases the radiation resistance of fuel rods. High chemical activity of lead, leading to significant corrosion of its interaction with the shell, can be reduced by introducing some additives lead [1].The calculations showed that in the fuel elements, when the gap between fuel and shell of 0.1 mm, the thermal resistance of liquid metal thermal interface layer is comparable to the thermal resistance of the boundaries of contact of the melt with fuel and shell. With increasing burnup, the thermal conductivity of the fuel will decrease and the thermal resistance will increase in connection with the accumulation on the surfaces of the fuel and shell of gaseous fission products and corrosion products of the interaction of the liquid metal, the shell and fuel. As a result, the temperature in the center of the fuel will increase.The above factors should be taken into account in the calculations of the thermal regime of the fuel rods and the reactor installation as a whole, and the thermal resistance of the contact boundary layer of liquid metal fuel and the cladding shall be experimentally investigated.
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